Wednesday's meeting between Iran and the world's six leading powers in Baghdad was hardly the stuff of breakthroughs, yet by the modest standards of diplomacy with Tehran, the fact that the two sides talked in detail about what divides them counted as progress of sorts.

Amid all the rhetoric, this dispute centres on one issue: Iran's insistence on its right to enrich uranium. This highly sensitive process could be used to produce uranium enriched to the 3.5 per cent purity needed to run nuclear power stations - and Iran adamantly maintains that is the sole aim - or to the 90 per cent needed for the fissile core of a nuclear weapon.

The safest option would be for Iran not to enrich at all, hence six United Nations resolutions make that demand. But the nuclear non-proliferation treaty (NPT) grants all signatories the right to enrich, provided they obey the relevant safeguards.

Iran says that it has every right to master this process, the West and its allies fear the consequences of Tehran effectively seizing the means to build nuclear weapons. Almost a decade of diplomacy has failed to bridge that yawning gap.

Wednesday's proposals fell into the category of what diplomats call "CBMs" - or "confidence building measures".

Iran has enriched about 110 kg of uranium to 20 per cent purity, a step closer to the level needed for nuclear weapons. When pressed for an explanation, it claimed to need this material for a civilian research reactor.

In fact, Iran lacks the technology to make the fuel for this plant. Western officials have concluded that Tehran has no conceivable use for uranium enriched to this level. So their opening proposal in Baghdad was for Iran to freeze production and hand over the existing stockpile of this material.

Regardless of whether Iran has any use for this substance, transferring a single gram would amount to a symbolic concession. Iran wants sanctions eased first - and its representatives have a strategy of their own. By dangling concessions, they are trying to break the unity of the six powers and peel off Russia and China from their Western counterparts.

Iran wants to divide its opponents; the group of six are trying to extract the material that Tehran's scientists have sacrificed so much to manufacture. If this fraught dispute is to be resolved, many sleepless nights of negotiation lie ahead.